numpy-discussion

[Numpy-discussion] ?Loading double and cdouble in an PyArrayObject?

[Norman S. <Nor...@mo...>]

How do I take data from a double array or a complex array as defined below and
initialize a Numeric array and load it appropriately?



struct complex {
  double real;
  double imag;
} complex;

complex cdata[100];
double *data[100];
PyArrayObject *array;

/* code where cdata and data are loaded up is not included *.


I think this is how I do it for doubles (correct me if I'm wrong).
  array = PyArray_FromDims(1, numData, PyArray_DOUBLE)
  for (i=0; i< 100; i++) {
      (double *)(array->data)[i] = data[i];
  }


How do I load the data in cdata into an PyArrayObject?


Thanks,
Norman Shelley

Re: [Numpy-discussion] ?Loading double and cdouble in an PyArrayObject?

[Francesc A. <fa...@op...>]

A Dimarts 07 Octubre 2003 17:58, Norman Shelley va escriure:
> How do I take data from a double array or a complex array as defined below
> and initialize a Numeric array and load it appropriately?
>
> struct complex {
>   double real;
>   double imag;
> } complex;
>
> complex cdata[100];
> double *data[100];
> PyArrayObject *array;

By reading the manual (page 65), I guess the best would be something like:

  arr = PyArray_FromDimsAndData(1, 100, PyArray_CDOUBLE, cdata)

Cheers,

-- 
Francesc Alted

Re: [Numpy-discussion] ?Loading double and cdouble in an PyArrayObject?

[Norman S. <Nor...@mo...>]

Francesc Alted wrote:

> A Dimarts 07 Octubre 2003 17:58, Norman Shelley va escriure:
> > How do I take data from a double array or a complex array as defined below
> > and initialize a Numeric array and load it appropriately?
> >
> > struct complex {
> >   double real;
> >   double imag;
> > } complex;
> >
> > complex cdata[100];
> > double *data[100];
> > PyArrayObject *array;
>
> By reading the manual (page 65), I guess the best would be something like:
>
>   arr = PyArray_FromDimsAndData(1, 100, PyArray_CDOUBLE, cdata)

If cdata is never to be freed, e.g. a Fortran COMMON block, then that is the
case.
I with to use PyArray_FromDims() and then load it up with data

I am assuming this may work for doubles (?)
aPyArrayObject = PyArray_FromDims(1, numData, PyArray_DOUBLE)
for (i = 0; i < numData; i++) aPyArrayObject.data[i] = doubledata[i];

But then I wondered how to load for COMPLEX?


>
>
> Cheers,
>
> --
> Francesc Alted

Re: [Numpy-discussion] ?Loading double and cdouble in an PyArrayObject?

[Francesc A. <fa...@op...>]

A Dimarts 07 Octubre 2003 18:24, Norman Shelley va escriure:
>
> If cdata is never to be freed, e.g. a Fortran COMMON block, then that is
> the case.
> I with to use PyArray_FromDims() and then load it up with data
>
> I am assuming this may work for doubles (?)
> aPyArrayObject = PyArray_FromDims(1, numData, PyArray_DOUBLE)
> for (i = 0; i < numData; i++) aPyArrayObject.data[i] = doubledata[i];
>
> But then I wondered how to load for COMPLEX?

Perhaps something like:

  struct complex {
    double real;
    double imag;
  } complex;
  complex cdata[100];
  double *data;
  PyArrayObject *array;
  
  array = PyArray_FromDims(1, numData, PyArray_CDOUBLE)
  data = array->data
  for (i = 0; i < numData; i++) {
    *data++ = cdata[i++];
    *data++ = cdata[i];
    }
    
should work (but not tested here). CDOUBLE means double precision complex.

Something similar would work for double precision:

  complex ddata[100];
  double *data;
  PyArrayObject *array;
  
  array = PyArray_FromDims(1, numData, PyArray_DOUBLE)
  data = array->data
  for (i = 0; i < numData; i++) {
    *data++ = cdata[i];
    }

-- 
Francesc Alted

Re: [Numpy-discussion] ?Loading double and cdouble in an PyArrayObject?

[Francesc A. <fa...@op...>]

A Dimarts 07 Octubre 2003 18:58, Francesc Alted va escriure:
Ooops, I realized that I've made an error (at least ;-)

>   data = array->data

should changed by

    data = (double *)array->data

-- 
Francesc Alted